ARGUMENTS name a pointer to a string containing the name
of the file to create.

mode the permission that the file should have

parent a pointer to the parent dentry for this file.
This should be a directory dentry if set. If this parameter
is NULL, then the file will be created in the root of the
debugfs filesystem.

value a pointer to the variable that the file should
read to and write from.

DESCRIPTION This function creates a file in debugfs with
the given name that contains the value of the variable
value. If the mode variable is so set, it can be read from,
and written to.

This function will return a pointer to a dentry if it
succeeds. This pointer must be passed to the debugfs_remove
function when the file is to be removed (no automatic
cleanup happens if your module is unloaded, you are
responsible here.) If an error occurs, NULL will be
returned.

If debugfs is not enabled in the kernel, the value
-ENODEV will be returned. It is not wise to check for this
value, but rather, check for NULL or !NULL instead as to
eliminate the need for #ifdef in the calling code.